Field of the Invention
The present invention relates to an identification and/or signature process.
The invention concerns public key cryptography. In this field, identification is a procedure enabling a receiving entity to obtain assurance of the authenticity of the identity of a transmitting entity. Signature is a procedure ensuring the authenticity of a message sent by a transmitting entity to a receiving entity.
The invention has numerous applications in health, transportation, telecommunications and banking. In general terms, the invention uses signature and identification schemes based on the difficulty of factorizing a large number, said schemes requiring the performance of operations essentially amounting to modular multiplications of large numbers.
For a given scheme, the number of modular multiplications to be performed by the person having to sign the message and prove his identity is a crucial parameter, particularly in the case where the security module in which are performed the cryptographic calculations is a smart card. For most known schemes, the number of multiplications necessary leads, in the case of placing on a smart card using a standard microprocessor, a relatively unrealistic calculation time with respect to the signature and penalizing for the identification. It is possible to obtain much more acceptable signature and identification times by giving the card a crypto-graphic coprocessor, but this choice doubles the price of the card.
One of the aims of the present invention is to adequately reduce the number of modular multiplications necessary for an identification and/or a signature, in order to arrive at schemes which can be used in a smart card not having an arithmetic coprocessor.
The present invention relates to an identification and/or signature process, which can be likened both to the identification and signature scheme of FIAT and SHAMIR and to the identification and signature scheme of GUILLOU and QUISQUATER. The process of the invention is directed at an interesting compromise between the number of multiplications to be performed by the party wishing to prove his identity and the party checking it and the number of secrets which the former must hold.